Golf ball manufacturers have been experimenting with various materials and manufacturing methods for golf balls over the years in an attempt to further refine the manufacturing process. Some examples of issues that manufacturers typically face during manufacturing include golf ball layer adhesion, golf ball printability, and golf ball durability. For example, most manufacturers use ionomer resins for at least one golf ball component because of their durability, rebound, and scuff resistance characteristics. The recent trend toward light stable cover materials, however, has introduced durability and adhesion issues, particularly between an ionomer resin inner cover layer and a polyurethane/polyurea outer cover layer. In fact, the inner components of most commercially available polyurethane golf balls are surface treated, e.g., corona discharge/silane dipping, to overcome the adhesion problems. The surface treatment, however, adds cost and time to the manufacturing process.
Printing and coating an outer surface of a golf ball may also impose manufacturing difficulties, due, in part, to the dimpled, spherical surface and the variety of materials needed to be printed upon. Thus, many patents have issued for various methods of printing on a golf ball or coating a golf ball. Regardless of the method, however, if the material used to form the surface layer is resistant to paint, ink, or the like, the golf ball cannot be adequately processed after forming. To obviate this problem, most outer surface layers are either primed or surface treated prior to coating and/or printing. For example, flame treatment, chlorination, corona discharge, and combinations thereof have been employed before post-processing to remove the problem of adhesion between the paint and the polyolefin substrate. Another disadvantage is that different substrates do not accept all types of paints or printing inks.
Moreover, most compositions used in golf ball layers have a particular cure time that lengthens the manufacturing process. For example, polyurethane compositions typically include a prepolymer component and a curing agent. When the polyurethane material is cast or molded onto the ball, sufficient time must elapse prior to further processing to allow the polyurethane composition to cure adequately, which increases manufacturing time and decreases productivity. In addition, if printing or painting is attempted too soon, i.e., the layer is not allowed to adequately cure, defects from wet transfer may occur.
Some manufacturers have attempted to use highly neutralized polymers in place of the typical cover layer materials, i.e., inner and outer cover layers, in an attempt to overcome the problems addressed above. Potential compatibility issues remain with these fatty acid-based highly neutralized polymers, such as those discussed in U.S. Pat. No. 6,329,458, however, due to their hydrophobic backbone moiety. For example, the fatty acids may vaporize during injection molding, generating a large amount of gas, which may lead to molding defects, including adhesion problems. In addition, the presence of this gas may also result in gas constituents settling on the surface of the molded object, which greatly lowers the paintability and post-processing of the object.
Thus, a need exists in the golf ball art for a material that facilitates post-processing steps like painting, coating, and printing. In addition, a need exists for improved golf ball layer materials that reduce or eliminate adhesion problems with other layer materials. Moreover, a composition that cures/dries rapidly to a tack free state will eliminate defects caused by wet transfer.